Monolithic Microwave Integrated Circuits (MMICs) are of great importance in science and technology. MMICs constitute key building blocks of communication technology. Furthermore they have recently been used as a key component of superconducting quantum processors (see e. g. L. DiCarlo, et al. in “Nature” vol. 460, 2009, p. 240-244). Function and failure analysis of such MMICs is of crucial importance for the design as well as for simulation verification and diagnostics (see C. Böhm et al. in “Microwave Symposium Digest IEEE MTT-S International”, San Diego, 1994, p. 1605-1608).
Knowledge of external port measurements (e.g. using a network analyzer) offers only limited insight. For error analysis the mw near-field distribution on the device gives much more insight and allows spatially resolved testing and improvement based upon experimental results. Therefore different methods have been developed to study the spatial distribution of the mw near-fields (see e. g. S. Sayil et al. in “IEEE Potentials” vol. 24, 2005, p. 25-28; S. K. Dutta et al. in “Appl. Phys. Lett.” vol. 74, 1999, p. 156-158; C. Böhm et al. in “J. Phys. D.: Appl. Phys.” vol. 26, 1993, p. 1801-1805; Y. Gao et al. in “IEEE Trans on Microwave Theory and Techniques” vol. 46, 1998, p. 907-913; Y. Gao et al. in “Microwave Symposium Digest, IEEE MTT-S International” vol. 3, 1995, p. 1159-1162; G. David et al. in “Electronic Letters” vol. 31, 1995, p. 2188-2189; T. Dubois et al. in “IEEE Trans on Instrumentation and Measurement” vol. 57, 2008, p. 2398-2404; T. Budka et al. in “IEEE Trans. on Microwave Theory and Techniques” vol. 44, 1996, p. 2174-2184; and R. C. Black et al. in “Appl. Phys. Lett.” vol. 66, 1995, p. 1267-1269).
These methods use diverse physical effects to measure the mw electric or magnetic field. They have in common that they scan the field distribution point-by-point by complex and time consuming measurement techniques
A simple MMIC structure has recently been used as a tool for quantum coherent manipulation of ultracold atoms on atom chips (see P. Böhi et al. in “Nature Physics” vol. 5, 2009, p. 592-597). The ultracold atoms are moved, depending on their hyperfine state, by the influence of mw near-field potentials created with the MMIC structure. However, a method of measuring the mw near-field has not been described by P. Böhi et al.
Ultracold atoms forming a Bose-Einstein condensate (BEC) have been used for measuring an external magnetic potential (DE 10 2005 023 937 A1). The BEC is confined in a magnetic trap, which is subjected to a superposition with the external potential to be measured. As a result, the spatial distribution (atom density) of the BEC is changed, which can be optically imaged.